From U.S. Pat. No. 6,085,391 B1, a cross lapper is known including a laying carriage movable transversely with respect to an output conveyor belt arranged below the output conveyor belt, and an upper carriage as well as a plurality of card web transport belts for transporting the card web over the upper carriage and the laying carriage into a laying nip formed at the laying carriage for depositing the card web on the output conveyor belt.
In the aforementioned cross lapper, a card web input region includes a belt inlet formed of web transport and laying belts (hereinafter card web transport belts), the belt inlet having a downwardly inclined input path with two adjacent belt sections of the card web transport belts. The belt sections joined at the entry into the belt inlet form a narrow inlet nip adapted to the web thickness and extend in the inlet path substantially in parallel or at an acute angle with respect to one another and so close together that they bilaterally guide or cover the web in the inlet path. In this cross lapper both card web transport belts are passed through the upper carriage and through the laying carriage.
U.S. Pat. No. 6,195,844 B1, EP 0 517 563 B2, U.S. Pat. Nos. 3,877,628, 5,285,554 B1, AU 2003254378 A1, U.S. Pat. No. 5,590,442 B1 and EP 1 010 786 B1 also describe cross lappers in which both belts transporting the card web into the laying nip at the laying carriage and depositing it on the output conveyor belt are passed through the upper carriage as well as through the laying carriage. The above-mentioned references are only a selection among a larger amount of references showing cross lappers of the same belt guidance structure.
The known constructions have a relatively complex extension of their card web transport belts, particularly on the upper carriage, where one of the card web transport belts supporting the card web winds around a deflection roller about more than 90° delimiting the inlet path at the lower end thereof. In the construction according to U.S. Pat. No. 6,085,391 B1, the arrangement is additionally complicated by the fact that the second card web transport belt is also passed through the upper carriage in a manner that it accompanies the first card web transport belt in the area of a downwardly inclined inlet path with a close spacing. All these known constructions have in common that the card web transport belt conveying the card web from the inlet of the cross lapper extends after leaving the laying nip at the laying carriage in a close distance to the output conveyor belt or even contacts the fleece deposited thereon, which can be disadvantageous for the fleece if the card web transport belt has a certain surface roughness due to the transport function that it is intended to have.
Thus, the applicant already proposed a cross lapper disclosed in US 2007/0175000 A1 having two main carriages movable transversely with respect to an output conveyor belt, in which the card web transport belt transporting the card web from the inlet of the cross lapper and through a downward inclined card web inlet extends through the upper carriage, but not also through the laying carriage, but is passed above same past the laying carriage. In the area between the upper carriage and the laying carriage this card web transport belt serves for covering the card web on the upper section of another, separate card web transport belt which extends through the laying carriage and is reversed there by 180° and whose lower section then covers the fleece formed on the output conveyor belt. This separate card web transport belt, which at the same time forms a first cover belt, is an endless belt and is tensioned by a tension carriage movable along with the laying carriage. A second endless cover belt also extends through the laying carriage, is reversed about 180°, mirrored with respect to the above-mentioned first cover belt and only serves for covering the laid fleece on the other side of the laying carriage. It is passed through the same tension carriage as the first card web transport belt.
Since the card web transport belt transporting the card web and covering same between the upper carriage and the laying carriage rests loosely on the card web only and extends past the laying carriage, it is not ensured at very high working speeds that the card web is drawn into the laying nip between the two deflecting rollers disposed in the laying carriage and wrapped by the cover belts. Moreover, the clamping pressure between the two transport belts enclosing the card web between the upper carriage and the laying carriage in a sandwich-type manner is not particularly constant and sometimes not high enough, and in the case of large path lengths of the laying carriage the transport belt can also flutter, thus leading to fiber blowing effects.